1. Field of the Invention
The present invention relates to a milking method in which at least one teat cup is connected to a teat of the animal to be milked and milked milk is discharged from the teat cup, and in which upon cessation of the flow of milked milk a cleaning medium is passed via a supply line into the teat cup. Furthermore, the present invention relates to an apparatus which is suited for carrying out the method and comprises at least one teat cup which communicates with a milk line conducting milked milk and in the interior of which a supply line ends via which cleaning medium which has been discharged from a cleaning medium source can be introduced into the teat cup.
2. Brief Description of the Prior Art
Such a method is, e.g., known from European Patent No. EP-A-0543 463. In this prior art, the supply line for cleaning medium is connected to a collecting means which has connected thereto various lines. One of said lines conducts a disinfectant. Another one of the lines conducts a rinsing liquid. Finally, a further line is connected to a source of compressed air. All of the above-mentioned media, i.e., disinfecting liquid, rinsing water and air for blowing and drying, are regarded as cleaning media in the sense of the present invention and permit in the prior art a multi-phase cleaning process in which the teat cup removed from the teat and hanging downwards is first sprayed with disinfecting liquid, then rinsed with water and finally at least predominantly dried by blowing out the interior of the teat cup.
The apparatus which is known from the above-mentioned prior art comprises a shutoff nozzle which is directly arranged below the teat cup in the milk line and on which the cleaning medium rests and is discharged through the shut-off nozzle into the interior of the teat cup when subjected to pressure.
In a further prior art which is known from International Application No. W099/66787, the cleaning medium is introduced into the interior of the teat cup upon cessation of the flow of milked milk, but prior to removal of the teat cup from the teat. The problem created by a mixing of the milked milk, which is drawn off through the milk line, with the disinfecting liquid sprayed onto the teat is to be avoided in said prior art by a valve whose valve body releases the supply line for the cleaning medium and, at the same time, tightly seals the part of the teat cup positioned below when viewed in the direction of flow of the milked milk. However, in this prior art as well the cleaning medium, i.e., first the disinfectant, optionally atomized with compressed air, and later possibly also cleaning liquid, is passed from a central feed line via the supply line to the interior of the teat cup.
In the last-mentioned prior art, the sealing of the line in the flow direction of the milked milk is particularly problematic. Even the slightest irregularities in the wall of the teat cup prevent a reliable seal and thus the imperative separation under the food law of cleaning medium in the form of disinfecting liquid and water, on the one hand, and of the milk obtained during milking, on the other hand.
During milking, a pressure difference is usually created between the udder and the teat tip accommodated in the teat cup. The milked milk is also drawn via this negative pressure from the teat cup via the milk line into the downstream lines and collecting containers. For a better discharge of the milked milk via the teat cups and the milk line into a central milking line, use is often made of milking gears, which e.g. in the case of cows consist of a unit of four combined teat cups, and which near the teat cup are equipped with openings for admitting air, in particular when there are milking gears provided with long lines for discharging the milked milk without use of separate milk-collecting pieces. In such milking gears the milked milk is directly passed from the teat cups into the remote central milking line. The air introduced via the openings during milking effects a decrease in the negative pressure that prompts the milk to exit from the teat into the teat cup.
The inlet openings for the pressure-reducing air simultaneously enable germs and dirt to enter therethrough. The air inlet openings must therefore be cleaned, not least because drawn milk may also get stuck at the inlet openings.
The present invention is based on the technical problem to develop a method of the above-mentioned type such that milked milk is more reliably protected from the penetration of dirt and germs. Moreover, the present invention is to indicate an apparatus which is suited for carrying out the method and with which dirt is easily and efficiently prevented from penetrating into and getting stuck in the milking apparatus.
As for the problem according to the method, it is suggested by the present invention that the above-mentioned method should be developed such that air is introduced via the supply line into the teat cup upon discharge of the milked milk. Therefore, the method according to the invention provides in the already known way for a cyclic change between the milking process, i.e. discharge of milked milk via a milk line, and the cleaning of the teat cup, optionally with preceding disinfection of the teat accommodated in the teat cup. However, in contrast to the already known prior art, both the cleaning medium and the air for reducing the pressure prevailing in the interior of the teat cup are supplied via a single supply line in the method according to the invention. Germs and/or dirt drawn in during the drawing in of pressure-reducing air in the milk gaining process towards the teat cup are thus automatically flushed out in the subsequent cleaning step and optionally killed by disinfecting liquid. The air drawn in for pressure reduction is introduced in the method according to the invention via the supply line which may have an end remote from the teat cup that is not directly adjacent to the strongly soiled portion located below the udder of the animal to be milked.
For solving the problem according to the apparatus, the above-mentioned apparatus is developed with the present invention by a valve to which a cleaning line communicating with a source, an air-fed pressure-reducing line, as well as the supply line, are to be connected and via which the supply line is selectively connectable to the cleaning line or the pressure-reducing line. In the apparatus according to the invention the supply line which is selectively connectable either to the source for cleaning medium or, however, to the source for pressure-reducing air is positioned between the inlet for air and the teat cup. Dirt which has been introduced via the pressure-reducing line and which passes into the supply line is thus automatically cleaned during cleaning of the teat cup. Not only bacteria and dirt that might have passed through a filter are thereby killed off or washed out, but the outlet opening of the pressure-reducing line on the teat cup is also cleaned and rinsed. The adhesion of milk residues to said place is thereby reliably prevented.
According to a preferred embodiment, the valve of the apparatus according to the invention comprises a valve body which can be moved from a first position in which the supply line communicates with the cleaning line, into a second position in which the supply line communicates with the pressure-reducing line. This embodiment creates a valve which can be cleaned relatively easily, so that also those parts of the apparatus according to the invention that are not rinsed and optionally disinfected in each cleaning phase by introducing cleaning medium can easily be subjected to a cleaning and/or disinfecting process, optionally after disassembly of the valve.
Preferably, the valve body which is accommodated within a housing comprises outlet channels which circumferentially surround the valve body. Furthermore, the valve body comprises at least one valve channel which communicates with the outlet channels in an intermediate position differing from the first and second positions. In this preferred embodiment, the outlet channels communicate with the surroundings, thereby discharging the fluids to the surroundings in case of a possible leakage in the valve. Hence, it is thereby prevented that cleaning medium, in particular water and disinfectant, pass into the teat cup and thus into the milk line and the downstream lines when the milked milk is drawn off.
Moreover, it is possible in the intermediate position to introduce cleaning or disinfecting liquid into the valve through the outlet channels formed in the valve housing, whereby with a corresponding design of the outlet channels a disassembly for the complete cleaning and disinfection of the valve might become superfluous.
This embodiment is of particular advantage when the valve body according to a further preferred embodiment of the present invention is equipped with a passage channel for cleaning purposes that is operative in the first position and with a pressure-reducing passage channel that is operative in the second position. For instance, in the intermediate position the pressure-reducing passage channel can also be rinsed and disinfected with cleaning and disinfecting liquid via the outlet channels.
The formation of a passage channel for cleaning purposes and of a pressure-reducing passage channel in the valve bodies offers the additional possibility of adapting the respective flow channels for the cleaning medium on the one hand and for the pressure-reducing air, on the other hand, in the valve. Lines leading to and away from the valve can therefore be designed in the conventional way. The volume of air admitted during the milking process for pressure reduction is preferably controlled by a pressure-reducing passage channel that is designed as a throttle.
Any contamination of the apparatus according to the invention by the air drawn into the apparatus is efficiently prevented in that an air filter is provided in the pressure-reducing line. For an improved discharge of the milked milk preference should additionally be given to the connection of the pressure-reducing line to a source of pressure, and particular preference should be given to the provision of a periodically controlled air inlet valve on the pressure-reducing line, so that atmospheric air or air with an overpressure can be introduced in pulsed fashion into the teat cup, which is conducive, on the one hand, to an efficient discharge of the milked milk and, on the other hand, to the build-up of an adequate negative pressure for drawing off the milk from the udder.
In particular upon start of the cleaning phase in a teat accommodated in the teat cup, preference should be given to the provision of a shut-off valve for shutting off the milk line. According to a preferred embodiment of the present invention, this shut-off valve is assigned to the milk lines of all teat cups in a milking gear comprising a plurality of teat cups. In this preferred embodiment, the milking gear is shut off at a central place relative to a milk collecting container positioned downstream with respect to the milked milk.